The aqueducts and masonry in general of this dis trict are executed in ruble work, excepting the prin cipal stones of the lock-work, which are of sandstone from the Clyde. In the regulating lock of Loch Leek+, the hollow quoins, from the difficulties at tending the land-carriage, are actually, constructed of cast-iron, being a new application of that British Manufacture in massive building. Over the Muco mer channel of the river Lochy, a very handsome stone-bridge of arches of fifty feet each has been erected. From the irregularity of the ground on this part ofthe track of the which is much cut up with mountain brooks, a number of aqueducts have been found necessary ; one, in particular, over the Loy, consists of a centre arch of 20 feet span, and two side arches of 10 feet each, and, owing to the width of embankment here, the arch is no less than 250 feet in length. But in this and other cases the side arches answer the purpose of passages un canal, and thus save the expence of bridges. Another very difficult and troublesome part of the navigation, occurs at East Moy, where like that of Poughfour Burn, on the eastern division, the water is allowed to flow into the canal, but the gravel and stones are intercepted, by a kind of cess-pool, form ed is the adjoining valley.
In our progress towards the western sea-lock of Loch ED, after passing the aqueduct of the Lower Banavie burn, we reach the famous chain or suite con sisting of EIGHT not unaptly termed " Nee TUNE'S STAIRCASE" by the artificers' and workmen. This majestic chain of locks was finished, excepting the gates, in 1811. The probable cost of these locks may be stated at about L. 50,000. They occupy a range of 500 yards, and rise altogether about 60 feet The common void or cavity of the ck-chambers is 40 feet in width, and the depth 20 feet ; the bottom, forming an inverted arch, gives the whole a very grand appearance, presenting the greatest .mass of masonry any where to be found as applicable to the purposes of a canal. After pass . .
ing this interesting part of the work, canal gets easily along Corpach Moss (to the House of Cor pach, the 'former seat of the Cameron of Loch eil). Here a double lock is situate, connected with a basin for shipping, measuring 250 yards in length by 100 yards in breadth, which joins the sea lock, and so communicates with the Western Ocean by two mounds projecting about 850 yards into Loch Eil, and completibg the inland navigation of the Caledonian Canal from sea to sea.
As before noticed, the operations of the canal have been hitherto chiefly confined to the east ern and western divisions, so as to render these subservient to • the operations of the middle or central division. The artificers have now been employed to a greater or less extent upon the mid dle part for two seasons, and the probability is, that the canal may be opened from sea to sea in about three years, or in 1820. But, in works of this kind, it is almost impossible to foresee every contingen cy, and much depends upon the annual extent of funds to be laid out, and the effect which may thereby be given to the works. Time must also be allowed for proving the banks, and puddle-walls, which, in all similar works, are found to leak in the first instance, and require the banks to be partially opened.
The expellee of this great work, up to the month of April 1816, by the Parliamentary Reports, ap pears to amount to about L. 600,000 ; and, in all probability, before it is opened from sea to sea, it will require the expenditure of L. 200,000 more, or L. 800,000 in whole ; independently of the expellee of the various improvements to be made for the na vigation, which experience alone can point out and determine, after the canal is opened.
To render the access from seaward to the canal more safe, and give every facility to the navigation, there will require to be beacons fixed, and buoys moor ed in various parts,:and even a light-house erected at Tarbetness, in the Murray Firth, and another, as a direction for the Sound, between the Islands of Mull and Kerrara. Nor will the full advantages of this
navigation be felt, until west Loch Eil is connected with Loch Shiel, and a passage found to the Western Ocean, in the direction of the districts of Ardnamu rachan and Moidart.
The question of the ultimate advantage of this work, has been, matter of much discussion. But, we believe, this may, at once, be restricted to the consideration of the propriety of the excess of dimensions above the depth of fifteen or sixteen feet, so as to admit almost the largest class of merchant ships, -using the Baltic and North Sea trade- Now, we think it was proper that it should be constructed up on a scale calculated to meet the increasing dimen sions of merchant vessels. For when the Forth and Clyde Canal was determined, in the year 1768, to be of the depth of eight feet, and the locks in pro portion to measure seventy-four feet in length, and nineteen feet in breadth, it was termed the " GREAT CANAL," and it is worthy of remark that its uncommon size, for that day, was considered un necessary and useless for the trade of the country The reverse of all this, however, has been found by experience; and if its dimensions could now be en larged and its depth increased to the rise of the tides of the Firth of Forth, or to the depth of sixteen feet, the benefit of that navigation to the country would be incalculably greater. The Commissioners for the Caledonian Canal certainly acted wisely, in keeping its dimensions large ; as this will be of great service In navigating vessels even of a middling size ; the force applicable to the trackage of ships being found to be in proportion to the quantity of the fluid compared to the bulk of the vessel. Al though the inducement for frigates and the smaller classes of his Majesty's ships of war passing through this navigation, does not appear very obvious, yet cases may occur when this may be found advisable ; and as there is an abundant supply of water from the lochs upon this line of canal for the wants of any sup posable lockage, it was certainly proper, in a national work, that such an event should be provided for.
The writer of this article has made frequent voy ages from the Firth of Forth to the Firth of Clyde by the Orkneys, and is well acquainted with all the tracks of that navigation ; and can easily imagine its dangers, in long winter nights, even with all the ad vantages of light-houses and accurate surveys of the coast. He has also repeatedly visited the works of the Caledonian Canal. With regard to the quality of the workmanship, he shall only mention, as a pretty conclusive circumstance with regard to the masonry, that, from end to end of this great work, he has not seen a single set or shake in the whole of the locks and walls. Upon the subject of the navi gation of a ship in the lochs or lakes, he cannot speak professionally ; but, upon one of these visits, he went over the whole line in company with a cap tain of the Royal Navy ; and although this officer did not much relish the idea of his ship putting about or tacking with eddy winds in these narrows, nor of being dragged along by the power of horses or of steam, yet he had no doubt as to the fitness of the na vigation for smaller vessels. Indeed, since the dis covery of the application of the Dairwinfon steam dragger, the practicability of this navigation, from Fort George on the east coast, to the Ferry of Cur ran, at the junction of Loch Eil and Loch Linnhe on the west coast, is reduced to a certainty, for all vessels which can pass the canal locks. And thus, we have the firmest conviction, that the Caledonian Canal will, in the end, be universally viewed, as a truly great and noble undertaking, issuing in the most solid benefits to the country. (11.11.)